The present invention relates to a transmitter/receiver apparatus having an application to microwave band communications such as satellite communication, and more particularly, to a miniature transmitter/receiver apparatus which is small enough to be installed in, for example, the feeder section of an antenna.
While the tendency to apply satellite communication channels to commercial communications is increasing, a prerequisite for facilitating such an application is reducing the cost and size of a transmitter/receiver apparatus. For example, a miniature transmitter/receiver apparatus which can be incorporated in the feeder section of an antenna, which is about 2 meters in diameter, is desired.
A transmitter/receiver apparatus which is applicable to commercial communications uses a microwave band, e.g., satellite communication. The transmit level is in the order of 1 watt. The receive level is more than 100 dB lower than the transmit level. Hence, it is very important with this type of transmitter/receiver apparatus to set up a sufficient isolation between discrete circuits in order to minimize interference from a transmit system to a receive system. However, for miniaturization and presupposing the overall dimensions of the apparatus housing, the freedom of circuit layout is so limited that a sufficient isolation between independent circuits is impractical.